Authenticity of Hadith

Although we have many Aḥādīth, not all of them are authentic. Some may be narrated by weak narrators, some may be narrated by strong narrators and have mistakes, and some may be complete fabrications. Assuming that we wish to know how the Prophet Muḥammad ﷺ practiced Islām, how do we we know which Aḥādīth from him …